Background: Primary Aldosteronism (PA) is common and associates with excess cardiovascular morbidity independent of blood pressure. Animal and in vitro studies have demonstrated that exposure to aldosterone and sodium leads to cardiac fibrosis and hypertrophy and this may, partly, be mediated by inflammation and oxidative stress. We aimed to clarify the effects of aldosterone excess on myocardial structure and composition in humans using contrast-enhanced cardiac MRI as well as explore potential underlying mechanisms for any observed differences. Methods.
Results: Twenty seven subjects with recently diagnosed (less than one year) PA and 54 matched essential hypertensive (EH) controls underwent gadolinium-enhanced cardiac MRI; non-infarct related myocardial fibrosis was identified by a diffuse pattern of late gadolinium enhancement (LGE). Patients also underwent assessment of pulse wave velocity (PWV) by applanation tonometry, measurement of superoxide anion in whole blood and C-reactive protein in plasma as well as measurement of resting blood pressure and 24 h urinary excretion of sodium. Subjects were well matched with no difference in severity nor duration of hypertension. There was a significant increase in the frequency of diffuse LGE in PA (67%) when compared to EH subjects (17%; P<0.0001) although no difference in LV mass or function. This finding was independent of blood pressure and multivariate logistic regression modelling confirmed the presence of aldosterone excess was the only independent predictor of myocardial fibrosis (P<0.01). PA subjects also demonstrated significantly greater carotid-femoral PWV as well as higher levels of superoxide anion and CRP than EH subjects.
Conclusions: These data demonstrate that PA patients demonstrate more frequent myocardial fibrosis; this finding is independent of blood pressure. This may be mediated through inflammation and oxidative stress. This study highlights the importance of specific targeting of aldosterone excess by medical or surgical means as well as blood pressure reduction to minimise cardiac morbidity in Primary Aldosteronism.
Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.